An air conditioning case of a vehicle, which defines an air passage therein, is generally arranged in the inside of an instrument panel of the vehicle. In the air conditioning case, water that condenses on a heat exchanger for cooling and rainwater that enters from an outside air introduction port exist. A drain hose is generally connected to the air conditioning case to drain such water from the air conditioning case to an outside of the vehicle.
An arrangement of the drain hose is usually limited by the layout of the vehicle. In some cases, the drain hose has to be arranged at positions where it is easily pressed or crushed by passenger's feet and luggage in a passenger compartment. If the drain hose is crushed and it is maintained for long periods of time, it is clogged. As a result, the water leaks from the air conditioning case to the passenger compartment.
To address such problem, it is proposed to use a hard pipe as the drain hose. Because the hard pipe does not have adequate flexibility, it needs a flexible joint member such as a rubber hose at a position corresponding to a corner or a bend in its arrangement route. Therefore, it results in increases in the numbers of component parts and manufacturing steps.